Far-i.r. reflectance spectra of M2IMCl6 complexes where M = Sn, Pt, or Te, have been used to estimate the half-bandwidths of the v3 vibration of the [MCl6]2– ions. The values are substantially lower than those found from absorption spectra of powdered samples but those for the tellurates are greater than those for the platinates and stannates. An earlier interpretation of the mull i.r. spectra is supported by these results.